It is old to utilize various types of well valves such as a safety valve shown in U.S. Pat. No. 3,782,461 or a gas lift valve shown in U.S. Pat. No. 3,760,832 which are moved to an open position by a first surface controlled force and are moved to a closed position by a spring. The spring closing force is adjusted at the factory during assembly by making internal adjustments, such as selection of a suitable spring, to adjust the closing force of the valve and consequently its opening force in view of its intended specific application. However, in the event that the opening and closing force specifications for a particular application change, the valve is returned to the factory, partially disassembled, and readjusted for use under the specified operating conditions.
The present invention is directed to a well valve in which a spring actuated closing force can readily be adjustable from the outside of the valve without dismantling the valve whereby adjustments may be made quickly and accurately in the field as well conditions change thereby avoiding the necessity of shipping the valve to the factory for disassembly and readjustment.